THEORY OF EVOLUTION 25 



in exactly the same sense as is the evidence from 

 comparative anatomy. It suffices to know that 

 there lived in the past a particular "group" of 

 animals that had many points in common with 

 those that preceded them and with those that 

 came later. Whether these are the actual an- 

 cestors or not does not so much matter, for the 

 view that from such a group of species the later 

 species have been derived is far more probable 

 than any other view that has been proposed. 



With this unrivalled material and splendid 

 series of gradations, paleontology has con- 

 structed many stages in the past history of the 

 globe. But paleontologists have sometimes 

 gone beyond this descriptive phase of the sub- 

 ject and have attempted to formulate the 

 "causes", "laws" and "principles" that have led 

 to the development of their series. It has even 

 been claimed that paleontologists are in an in- 

 comparably better position than zoologists to 

 discover such principles, because they know 

 both the beginning and the end of the evolu- 

 tionary series. The retort is obvious. In his 

 sweeping and poetic vision the paleontologist 

 may fail completely to find out the nature of 



